1. Field of the Invention
The present invention relates to a laser holder for holding a semiconductor laser. The present invention also relates to an optical pickup provided with such a laser holder.
2. Description of Related Art
Optical pickups have conventionally been used for reading information recorded on Blu-Ray discs (“BDs”), digital versatile discs (“DVDs”), compact discs (“CDs”), and other optical disks; and for writing information onto such disks. The optical pickup is provided with a semiconductor laser for directing laser light onto the optical disk.
CAN-package-type and frame-type semiconductor lasers provided to the optical pickup are known in the art. The structure of CAN-package semiconductor lasers is such that a semiconductor laser chip is mounted on a metal stem and protected by a cylindrical metal cap. In order for laser light to be emitted, the cylindrical metal cap has, e.g., a structure in which a glass window is provided, or a structure in which an aperture is formed. Frame-type semiconductor lasers are of a structure in which a semiconductor laser chip is mounted on an upper surface of a plate-shaped metal frame and a resin is outsert-molded so as to enclose the semiconductor laser chip on the metal frame.
When mounted on the optical pickup, the semiconductor laser is sometimes mounted on a laser holder and the laser holder is attached to a base member of the optical pickup. With such a configuration, using a laser holder made of metal enables more heat generated by the semiconductor laser to be dissipated.
The structure of CAN-package semiconductor lasers facilitates secure press-fitting in the laser holder. Accordingly, in the case that a CAN-package semiconductor laser is used, the laser holder and semiconductor laser are caused to make firm contact with each other, and desired heat dissipation performance can be ensured.
Secure press-fitting is also possible when a frame-type semiconductor laser is used, as described in Japanese Patent Application No. 2008-146785. Nevertheless, in the case that a frame-type semiconductor laser is securely press-fitted in a laser holder, the plate-shaped metal frame may deform. In the worst case, the semiconductor laser chip mounted on the metal frame may get dislodged. Even if the semiconductor laser chip does not get dislodged, the performance of the semiconductor laser may be adversely affected.
Accordingly, in the case that a frame-type semiconductor laser is used, an urging member is sometimes used in order to cause the laser holder and the semiconductor laser to make firm contact with each other; e.g., as described in Japanese Patent Application No. 2007-12138. In another configuration example involving the use of a frame-type semiconductor laser, heat-dissipating grease is sometimes used if it is impossible to cause the laser holder and the semiconductor laser to make firm contact with each other.